Glutaconic acid is an α,β-unsaturated C5-dicarboxylic acid (2-pentenedioic acid) that accumulates in individuals with glutaric acidemia type I (Hoffmann G F, Zschocke J (1999) Glutaric aciduria type I: from clinical, biochemical and molecular diversity to successful therapy. J Inherit Metab Dis 22:381-391). Glutaconic acid together with a diamine can polymerize to a polyamide related to Nylon®. The ideal material for biotechnological production of glutaconic acid would be glutamic acid, which can be produced by sugar fermentation. The chemical deamination of α-amino acids to α,β-unsaturated acids is very difficult. On the contrary, the strictly anaerobic bacteria Acidaminococcus fermentans and Clostridium symbiosum can easily deaminate glutamate via α-ketoglutarate, (R)-2-hydroxyglutarate, (R)-2-hydroxyglutaryl-CoA, and glutaconyl-CoA to (E)-glutaconate (Buckel W (2001b) Unusual enzymes involved in five pathways of glutamate fermentation. Appl Microbiol Biotechnol 57:263-273). A. fermentans and C. symbiosum are not suitable for the production of glutaconic acid because they decarboxylate glutaconyl-CoA to crotonyl-CoA. Genetic manipulation of these organisms has not been established yet. Thus, the genes coding for glutaconyl-CoA decarboxylase cannot be attenuated to a low level, whereas a complete deletion would deprive these organisms of the ability to produce ATP. Furthermore, the ultimate aim is the production of glutaconate not from glutamate but from glucose, on which A. fermentans and C. symbiosum are not able to grow.
The object of the present invention is therefore to provide a suitable method for the fermentative, biocatalytic production of glutaconic acid and related dicarboxylic acids or corresponding salts thereof.